1. Field of the Invention
The present invention is directed to a clutch system comprising a clutch arrangement and an adjusting device for actuating the clutch arrangement, which adjusting device is controlled by a control device for carrying out actuation processes.
2. Description of the Related Art
Clutch systems of the type mentioned above, which are also generally known in the prior art as automatic clutch systems, are increasingly used in motor vehicles. In order to engage or release the clutch at the correct time and with the correct speed, particularly also so as to be synchronized with the shifting processes to be carried out in a transmission, the control device, which ultimately activates the adjusting device for carrying out determined adjusting processes by means of corresponding signals, must obtain information about the instantaneous operating state of the clutch. For this purpose, it is known to detect the release path of the clutch, for example, by detecting the release position of a slave cylinder of a fluid clutch release system. There is generally a definite relationship between a release position of the type mentioned above and the operating state of the clutch and, therefore, the coupling moment or clutch torque which is transmitted instantaneously or the maximum clutch torque which can be transmitted. However, this relationship is not constant over the operating life of a clutch due to wear and can also change, for example, due to temperature in the area of the clutch. As a result of a change in the relationship, initially assumed to be fixed, between the movement or the position of a clutch release element and the clutch torque which is actually transmitted via the clutch, the clutch is adjusted too soon or too quickly, for example, beyond an operating position in which or after which the clutch starts to transmit torque proceeding from a completely released position. This can result in engagement shock which can lead to excessive wear when it occurs frequently and, at the least, can cause an unpleasant sensation for the driver of a vehicle outfitted with a system of this kind.
It is the object of the present invention to provide a clutch system in which an actuating process of a clutch arrangement can be implemented with increased precision.
According to the present invention, this object is met by a clutch system comprising a clutch arrangement, an adjusting device for actuating the clutch arrangement, which adjusting device is controlled by a control device for carrying out actuation processes, a displacement sensor arrangement for detecting a first quantity relating to the movement of a component which displaces when an actuating process is carried out, and a torque sensor arrangement for detecting a second quantity relating to a clutch torque transmitted via the clutch arrangement, wherein the control device controls the adjusting device for carrying out actuating processes at least occasionally depending on at least the second quantity.
According to the present invention, the detected torque transmitted via the clutch or a quantity relating to the latter is included at least occasionally in generating a control signal for the adjusting device. When engaging and releasing processes are carried out, particularly in connection with a gear shifting process, the torque actually transmitted via the clutch is a determining quantity for carrying out the fastest possible gear shifting processes on one hand and to achieve the most comfortable possible shifting process on the other hand. Accordingly, by taking this quantity into account at least occasionally, it can ultimately be ensured in a clutch torque control loop that the torque, which is transmitted or which can be transmitted via the clutch corresponds exactly to a clutch torque to be provided for a determined shifting process or other operating state of a vehicle.
According to the invention, the control device can control the adjusting device based on the second quantity when carrying out an actuating process. Alternatively, it is possible for the control device to control the adjusting device occasionally based on the first quantity and occasionally based on the second quantity. For example, the control device can control the adjusting device based on the first quantity in one phase of an actuating process in which an actuation of the clutch arrangement has essentially no influence on the clutch torque.
Phases of an actuating process in a friction clutch in which an adjustment of the clutch arrangement has essentially no influence, i.e., possibly only a slight influence, on the clutch torque are, for example, phases in which the clutch is moved from a completely released position toward a slip point, that is, to an operating state after which the clutch starts to transmit torque. In this noncritical range, a comparatively rough adjustment, but one which is or can be carried out quickly, can be performed based on the quantity relating to the displacement path. When the clutch approaches the critical operating state, there is a transition in the next phase to torque regulation in which the determining quantity for further adjustment of the clutch is the clutch torque. Also, in this state in which the clutch torque, i.e., the torque transmitted via the clutch, is in the range of the maximum driving torque that can be generated by a drive unit but has not yet reached the maximum torque that can be transmitted via the clutch, a comparatively fast adjustment can be carried out, for example, in the direction of a completely engaged position.
In order to provide a certain degree of redundancy, i.e., increased safety, when actuating the clutch arrangement, it is suggested that the control device controls the adjusting device at least occasionally based on the first quantity and the second quantity when carrying out an actuating arrangement. When the two quantities are utilized simultaneously for correct actuation of the clutch arrangement, it can be provided, for example, that the sum, the product, the sum of the squares, and so on, of the two quantities are formed and a quantity is accordingly obtained on the basis of which an engagement process or a releasing process can be carried out.
Regardless of whether the first quantity is used occasionally by itself or together with the second quantity for carrying out an actuating process, it can be provided according to a further advantageous feature of the present invention that a change in the operating state of the clutch system, preferably wear occurring in the area of the clutch arrangement, is determined on the basis of the first quantity.
For example, if it is not compensated by a readjusting device, the wear occurring in a clutch arrangement leads to a displacement of different components which can be determined, for example, in a defined state. This defined state can be a completely engaged state, for example. Based on this information on the operating state of the clutch, that is, for example, information about wear, readjusting steps can be initiated in the clutch release system or, for example, corresponding compensation steps can be triggered in the clutch arrangement. Further, it is possible to generate a warning for the driver when a maximum permissible wear is detected.
According to the invention, the displacement sensor arrangement preferably detects the displacement of a clutch release component. For example, the clutch release component can be a release piston of a release piston-cylinder arrangement.
According to another feature of the present invention which is advantageous particularly with respect to simplified assembly, the displacement sensor arrangement and the torque sensor arrangement are joined in a subassembly or constructional group.
For example, the torque sensor arrangement can have a sensing or pickup area which scans a code provided at a clutch output shaft. In an embodiment form which is particularly advantageous with respect to electrical connection, the pickup area can be fixed axially with respect to the clutch output shaft. Alternatively, however, it is also possible that the pickup area is axially displaceable with a clutch release component, preferably a release piston of a release piston-cylinder arrangement. Accordingly, the pickup area moves in axial direction when carrying out an engagement or release process and, in so doing, can, in addition, supply a signal representing the release path. Accordingly, the displacement sensor arrangement and torque sensor arrangement are integrated in this instance.
Further, according to the present invention, a method is provided for actuating a clutch arrangement which can be actuated by an adjusting device, comprising the following steps:
a) detection of a first quantity relating to the displacement path of a component which moves when the clutch arrangement is actuated;
b) detection of a second quantity relating to a clutch torque transmitted via the clutch arrangement;
c) at least occasional control of the adjusting device for actuating the clutch arrangement based on at least the second quantity.
In this method, the adjusting device can be controlled occasionally based on the first quantity and occasionally based on the second quantity. Alternatively, it is possible that the adjusting device is controlled at least occasionally based on the first quantity and the second quantity.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.